Dark matter is "dark" because no one knows what it is and a blanket term for whatever outnumbers particles of regular matter by more than a factor of 10 is necessary.

Because it can't be detected, dark matter is inferred by gravitational influence in galaxies, and by measuring the mass of a nearby dwarf galaxy called Triangulum II, Assistant Professor of Astronomy Evan Kirby says they may have found the highest concentration of dark matter in any known galaxy. 

Research provides first ever weather map of a planet outside our solar system and it finds wind hurtling at speeds 20x faster than ever recorded on Earth - and seven times the speed of sound.

The researchers measured the velocities on the two sides of HD 189733b and found a strong wing moving at over 5400mph blowing from its dayside to its night side. The velocity was measured using high resolution spectroscopy of the Sodium absorption featured in its atmosphere. As parts of HD 189733b's atmosphere move towards or away from the Earth the Doppler effect changes the wavelength of this feature, which allows the velocity to be measured.

A team of astronomers have discovered an extremely rare galaxy of gigantic size. The galaxy,  J021659-044920
and located about 9 billion light years away towards the constellation Cetus, emits powerful radio waves and has an end to end extent of a whopping 4 million light years. 

In a bit less than two days an orbiting object known with the peculiar name of WT1190F - but I'd like to rename it as WTF 1190 for obvious reasons - is expected to fall on Earth. The object was discovered by the Catalina Sky Survey in 2013 and little is known about its origin. It has a low density and makes a very eccentric revolution around us every three weeks. 
Below is a picture taken by the University of Hawaii 2.2 meter telescope in October. The object is observed as a bright spot that shows a relative motion with respect to fixed stars.

The long, shallow grooves lining the surface of Phobos are likely early signs of the structural failure that will ultimately destroy this moon of Mars.

Orbiting a mere 3,700 miles (6,000 kilometers) above the surface of Mars, Phobos is closer to its planet than any other moon in the solar system. Mars' gravity is drawing in Phobos, the larger of its two moons, by about 6.6 feet (2 meters) every hundred years. Scientists expect the moon to be pulled apart in 30 to 50 million years.

"We think that Phobos has already started to fail, and the first sign of this failure is the production of these grooves," said Terry Hurford of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

In 2006, a tiny percentage of astronomers took it upon themselves to change the definition of "planet" and so Pluto was out. Chaos ruled, the 237 astronomers who made the ruling dug in their heels, and for the most part they were ignored.

After all, there are now nearly 5,000 planetary bodies orbiting stars other than ours. But astronomers don't know what exactly we should call them. Today at an American Astronomical Society meeting, UCLA professor Jean-Luc Margot described a simple test that can be used to clearly separate planets from other bodies like dwarf planets and minor planets and replace the  "definitional limbo" those bodies are in. 

Let's declare Pluto as a dwarf or sub dwarf planet AND a planet! This is about the vexed question of whether Pluto is a planet or not. Yes the International Astronomical Union "settled the question" but I'm not sure their decision is one that will work all the way into the future, for instance if we find Earth or Neptune sized objects beyond Pluto. And it also stretches language in an awkward way to say that Pluto is a dwarf planet but not a planet - and the English word "dwarf" seems to have little to do with the concept of clearing your neighbourhood.

SETI has listened to KIC 8462852 for two kinds of signals and found nothing stronger than an intensity of 100 Jy (Jansky). They looked for purposefully broadcast narrow band signals and a wide band omnidirectional signal not purposefully sent.  Their first observational pass lasting two weeks found , in their words, "To summarize these observations, we estimate an upper limit for anomalous flux from KIC 8462852 to be 100 Jy in a 100 kHz band over the frequencies displayed." 1  Put another way either no one is transmitting, or no one there is transmitting anything strong enough for us to detect at the distance KIC8462852 is from us (about 1500 light years).  

Weather patterns in a mysterious world beyond our solar system called
PSO J318.5-22
have been revealed for the first time. Layers of clouds, made up of hot dust and droplets of molten iron, have been detected on a planet-like object found 75 light years from Earth, researchers say. 

Findings from the study could improve scientists' ability to find out if conditions in far-off planets are capable of sustaining life, the team of astronomers suggests.

They used a telescope in increasingly-popular Chile (Hawaii and Arizona in the U.S. long ago declared white-collar astronomy and a mandated lack of light pollution to be environmentally hazardous) to study the weather systems in PSO J318.5-22, which is estimated to be around 20 million-years-old. 

I got many comments on last week's Nibiru article from some very scared people. They needed a lot of reassuring that it was indeed a hoax and not real, and brought up many topics to discuss such as lens flares, hoaxes, double sun videos, rare sun mirages, and the status of the astronomical search for various versions of planet X. Why are astronomers so sure that Nibiru is nonsense?